Non-naturally occurring amino acids are used as pharmaceutical intermediates and precursors for combinatorial synthesis. The large number of recent drug candidates based on non-naturally occurring amino acids has created strong demand for these key pharmaceutical building blocks. The proposed research focuses on the development of a transamination process for the production of non-naturally occurring amino acids. The process is a chiral synthesis, not a resolution, leading to efficient use of carbon and reduced waste, and the technology may be applied broadly to produce a wide range of amino acid targets. High chemical yields can be achieved from simple, inexpensive precursors. The method has been demonstrated with four target non-naturally occurring amino acids having immediate commercial applications. To provide sufficient enzyme for preparative-scale reactions and establish the means for commercial production, genes encoding key transaminases from different classes and including D-transaminases will be cloned and expressed. The production of both D- and L-amino acids will be demonstrated on the 100 gram scale. Immobilization methods will be optimized. An improved method for driving the reaction to completion will be implemented by incorporating a decarboxylase into the biocatalyst. Finally, the stereoselective production of 8 different 15N-labeled amino acids will be demonstrated. PROPOSED COMMERCIAL APPLICATIONS: Production of non-naturally occurring amino acids for pharmaceutical intermediates; building blocks for peptide analogs and for combinatorial synthesis